Expansion-engine for reducing compressed gas to low temperatures.



C. W. P. HEYLANDT.

EXPANSION ENGINE POR RBDUOING OOMPRESSBD GAS T0 LOW TEMPERATURES.

APPLIOATION FILED JAN. 29, 1910.

Patented Mar. 12, 1912.

/N vE/v mfr W/T/VESSES 7/ 7 @264 CHRISTIAN WILHELM PAULUS HEYLANDT, OF HAMBURG', GERMANY.

EXPANSION-ENGINE FOR REDUCING COMPRESSED GAS T0 LOW TEMPERATUBES.

Specification of Letters Patent.

Patented Mar. 12, 1912.

Application filed January 291910.4 Serial No. 540,901.

To all whom 'it concern:

Be it known that I, CHRISTIAN WILHELM PAULUs HEYLANDT, a subject of the Emperor of Germany, residing at Hamburg, in the Empire of Germany, have invented new and useful Improvements in Expansion-Engines for-Reducing Compressed Gas to Low Temperatures, of which the following is a specification.

My invention relates to expansion engines, in which highly compressed gas is caused to expand while performing work, so that it cools down to a very low temperature.

The object of the invention is to substanf tially prevent the heat caused by the friction of the piston reaching the expanded gas and yet to prevent freezing in of the piston and trouble with lubrication by reason of the extreme cold.

My invention consists in improvements in such expansionv engines, whereby the indicated defects are avoided and the-operation of the machine is rendered exceedingly reliable.

One improvement consists in a long pis- .t0n made in twoportions secured together with a packing ring between them. One portion of the piston working in the cold sphere of the .expanding gas is so fitted into the cylinder as to leave almost no annular space around it without, however, producing any friction. It comprises in its interior a space, which may either he filled up with a had heat conductor, or form a vacuum chamber, from which the air has been exhausted. Owing to this construction of the said piston portion and also on account of the said packing ring .the expanding` volume of cold gas can not come in Contact or become mixed with lubricants, such as oil, naphtha, gasolene, etc. The other portion of the piston is fitted to slide in the cylinder and requires to be lubricated like ordinary pistons. It serves also for centering the first mentioned portion, so as to prevent' this from rubbingon the walls of the cylinder. To better insure this effect the cylinder is preferably placed vertically and the inlet and outlet valves for the compressed gas are disposed at the top of the cylinder. A

Anotherimprovement consists in a coil, through which is passed gas or air at ordinary temperature, surroundingthe cylinder in the vicinity of the lubricated portions for recovering some of the cold thatl reaches there and thereby prevents the cylinder from cooling below a certain limit by giving heat to the cylinder so that in this manner the lower portion of. the piston is surely prevented from freezing in and stopping.

I shall now proceed to explain the apparatus more in detail with the aid of the accompanying drawing showing a diagram of the piston, cylinder, and immediately related parte. The part a represents a steel cylinder with thin walls, on which the admission valve b and the exhaust valve c are mounted. The iston d moves in the cylinder a, into whlch it is very closely fitted. At a suitable point of the said piston, preferably at the point d1, a tight packing ringhas been provided. An extension of the piston d is formed by the piston cl2, which without friction moves in the cylinder a, and is centered in its motion by the piston d. Piston d2, however, is'so constructed that there is no considerable annular space between the said piston and the cylinder a. Valve rods indicated by e1 and e are used for operating the valves b and 0. The conduits used for recovering the cold are indicated by f and f1.

In operating the engine as will be well understood compressed, purified, dry gas is admitted to the cylinder a through the valve b when the piston part d2 is-in the upper part of the cylinder'. The` downward motion of the piston after closing the inlet valve causes an ideal expansion of the compressed gas work being performed at the same time, and the obtainable reduction in temperature amounts for example to over 200 C., according to the ratio of pressure and the contents of the cylinder. While the piston is on its upward stroke the cold gas is exhausted through the valve c. The aforementioned large reduction in temperature is obtained partly on account of the fact that the piston part (Z2 moves without friction in the cylinder a. the cold produced being consequently not diminished by heat generated by friction. Transmission of heat through the piston to the cold. expanded gas is reduced to a minimum by either creating aivacuum the hollow piston d2 or making it. of a material which is a had heat conductor. The side Walls of the cyliuder a are made so thin that, although capable of withstanding the operating pressure. the cross section of the walls is so 'small that the heat can nd its Way to the I into the inner` conduit f and flowing there in an upwardv direction, thereby absorbing a part of the cold which passes through the wall of the cylinder a, so as to make. it possible to utilize it again for the operation of the device in as much as the heat, owing to the compression of the gas flowing in the conduit,` is transferred to thecylinder wall the-device.

whereby thengasentering the admission valve b by means. of a pipe (not shown) connecting the outlet branch of the conduit f with the channel leading to the admission pipe Z), a temperature near to the ordinary temperature -frequired is obtained. This arrangement thus oi'ers a means of utilizing for cooling purposes the cold which unavoidably escapes in undercurrents of defects of insulation.

lThe free space g between the cylinder a and the coilsf surrounding it on one side and the outer wall surrounding the whole apparatus and the other coils f1 is filled with insulating material.v The sliding piston part d, with its tight packing ring d1 operates, in consequence ofthe installation of the conduits f, at moderate temperature, and can consequently be lubricated with ordinary lubricants, andl as its guide surface isnot within the cold sphere, the cold gas does not get mixed or contaminated with the lubricating oil, an advantage which is also partly due to the vertical position of The current of gases in the conduits f and f1, which are slightly cooledv during their circulation, may be used for the preliminary cooling of other volumes of compressed gas'. It is l'known that such preliminary cooling increases the eiiiciency of air liquefying machines (or gas liq'uefyinofmachines).

`The freezing in and consequent stopping of the apparatus are prevented by leaving only the lend section of the piston, which operates without lubrication, exposed to the iniuenceof the very low temperature, and by preventing the transmission of much cold to the .sliding parts of the piston, which rev quire lubrication, by insulating the said piston part by a vacuum, and byv providing the piston, if necessary, with conduits which aiford a4 means of recovering the escaping cold by transmitting it to gas currents, and of -preventing-the sliding piston from becoming cold.

What-I claim is 1. An expansion engine for` reducing compressedL gas to low temperatures, thevv combination with a cylinder of two valves for one end of said cylinder, one for the inlet of compressed gas and the other for the outlet of cold expanded gas, a coil surrounding said cylinder at points remote from said end adapted for collecting cold leaking through said walls, a piston consisting of two portions, of which one working in the cold sphere of the expanded gas is a bad heating conductor and is so fitted into .said cylinder as to move without substantial friction and the other portion is fitted to slide in said cylinder, anda packing ring for said piston substantially as set forth.

p 2. In an expansion engine for reducing compressed gas to low temperatures, the combination of a cylinder having thin walls,

of two valves for one end of said cylinder, i

one for the inlet ofcompressed gas and thes other for the outlet of cold .expanded gas, a cold collection coil surrounding said cylinder, a piston consisting oftwo portions of which one working in the cold sphere of the expanding gas is adapted to form a bad heat 90. conductor and is fitted within said' cylinder so as to move withoutv substantial friction and the other portion is adapted to slide in said cylinder, and a packing ring for the lower portion of said piston.

3. In an expansion engine for reducing compressed gas to low temperatures, the combination with a vertical cylinder of 4two valves for the top of said cylinder, one for the inlet of compressed gas'y and the other for the-outlet of cold expanded gas, a cold absorbing coil surrounding said cylinder, a piston consisting of two portions, one work'- ing in the cold sphere of the expanding'gas and adapted to .formv a poor heat conductor and fitting within vsaid cylinder so as to move without substantial friction therewith, the other portion is fitted to slidel in said cylinder and a packing ring between the two portions of said piston.l

4. In an expansion engine for reducing compressed gasto low temperatures, the combination of a vertical cylinder having i upright walls, of two valves for the top of said cylinder, one for the inlet of compressed gas and the other for the outlet of cold expanded gas, a cold absorbing coil surrounding-said cylinder, a piston consisting of two portions, one formlng abad heat conductor adapted tomove within'said cyl- 120' cylinder remote from said end, said piston In testimony whereof I have signed this having an extending portion which extends specification in the presence of two Sub- 10 into thle1 cold slhere 0%1 thelclnder and subfj scribing witnesses.

stantia y insu ates t e si in ortion o the piston therefrom and measpfor trans- CHRISTIAN WILHELM PAULUS HEYLANDT mit-ting cold from the portion of the cylin- Witnesses:

der with which said piston makes sliding HENRY HASPER, contact. WOLDEMAR HAUPT. 

